Weighted silk and method of weighting the same



Patented Mar. 21,

UNITED STATES PATENNT- OFFICE VICTOR IBOEIJOIE'ER, OF BIJJGEWOOD, NEW JERSEY, ASSIGNOR T TEXTILE DYEING AND PRINTING CO. OF AMERICA, INC., A CORPORATION OF NEW JERSEY WEIGHTED SILK AND METHOD OF WEIGHTING THE SAME ll'o Drawing. Application filed July 27,

The invention is applicable to the weighting of natural silks either in the skein or piece, and to pieces containing natural SllkS in admixture with other fibers.

6 The invention will be illustrated in application to natural silk in the piece.

In accordance with my fprocess, the Silk to be weighted is first Ere erably sub ected to the usual boiling 0 and is thereafter 10 weighted with a compound containing tin and oxygen. The first step in the weight ng process consists in subjecting the piece to an aqueous solution of a soluble tin salt. This is preferably carried out by packing a numher of pieces in a rubber lined centrifuge basket, rotating the basket at a low speed, and running the solution into the basket at such a rate as to substantiall fill the same. The rotation of the basket orces the solution uniformly through the pieces, and when sufiicient time has elapsed to insure that the pieces are thoroughly and uniformly impregnated with the solution, the introduction of fresh solution is terminated. The

basket is then rotated at a higher speed to drive off the excess of solution over that which has been absorbed by the silk fibers.

While the water soluble salts of tin are generally applicable to my purpose, the salts preferably employed are those utilized in the usual tin weighting process, such as the tetrachloride or ammonium stannic chloride. The tetrachloride appears to be best suited and is usually employed for this purpose in a solution made up to a gravity of from 18 to 30 B. measured at 16 C.

The next step of the process consists in weighting or impregnating the fibers with an oxide of tin by conversion of the absorbed t0 tin salt. While this may be accomplished by sub'ectin the fibers to the action of a base a apted to combine with the acidic component of the tin salt, as for example by subjecting the fibers to the action .of gaseans ammonia, it is preferably acomplished by washing the pieces with water This hydrolyzes the tin salt and results in the production of a tin oxide, uniformly distributed throughout the silk fibers.

The pieces may. after this treatment be 1982. Serial No. 625,220.

immediately subjected to the lead weighting cycle hereinafter described, but are preferably given a further treatment adapted to fix the tin oxide, viz., to convert it to a more stable form and to impart additional weight. For this purpose, the pieces are passed into an aqueous solution carryin an acid radical or compound adapted to orm a water insoluble compound with the tin oxide. Boric and/or phosphoric acid may be employed for this purpose, but the usual materials are sodium and potassium phosphates, silicates and tungstates, and the mono or di-ammonium phosphates. Of these materials sodium phosphate has been found to be the most satisfactory, and this step may conveniently be carried out by passing the pieces through a'solution of sodium hosphate of about 6 Be. at a temperature 0 about 65 C. This treatment appears to result in the direct fixation of sodium phosphate by the tin oxide present in the silk fibers, and not only imparts greater weight to the silk, but converts the tin present to a very stable form havin desirable physical characteristics. The formation in the fibers of simple tin phosphate or ofa complex tin-alkali metalphosphate will be enerally referred to as the formation of a tin phosphate. The complete cycle of operations involving impregnating the fibers with a tin oxide and thereafter converting this oxideto a stable water insoluble tin salt is called a pass.

From one to four or more passes may be applied to the pieces, although from three to four passes are satisfactory for the purposes of the present invention. subjecting the pieces to one or more passes of the type mentionedwill be hereinafter generically referred to as weighting the silk with a Water insoluble compound containing tin and oxygen. The term water insoluble compound containing tin and oxygen will be employed to connote both an oxide of tin and-the more complicated salts, contai'ning in addition acid radicals formed by the oxidation of metal and metalloid elements, as well as the cornplex salts formed by the direct fixation of water soluble salts by the tin oxide.

The next step in the process consists in a special procedure which I have invented for further weighting the pieces and imparting certain desirable characteristics thereto. This procedure involves further weighting the pieces with a compound containing lead and oxygen. lVhile the Water soluble lead salts cannot be efliciently employed for weighting silk in the first instance, they may be efficiently employed for imparting further weight after the silk has been initially weighted with a compoundcontaining tin and oxygen. For example, Waldstein and Peter, I]. s. Patent 523,560, July 24., 1894, disclose that silk fibers which have been passed through a solution of tin salts can be further weighted by passage through a solution of lead acetate; and Renard, Carron, Bonnet & Co., French Patent 258,869, disclose that silk goods which have been subjected to a complete tin pass may be further Weighted by passage through a solution containing soluble lead salts.

For this purpose, the pieces are washed and are then preferably passed throu h a solution of lead acetate of about 25- (measured at 60 C.) at a temperature of application of about 60 C. The pieces are again washed in the usual manner. Up to this point the procedure described has been usual and constitutes a part of my invention only insofar as it is utilized in combination with the succeeding steps which characterize and distinguish the same.

In accordance with my invention, the pieces are now subjected to an aqueous solution containing sodium or potassium borate. The borate appears to be fixed by the tinlead compound with which the silk fibers are already impregnated. and not only imparts an additional weighting effect. but also converts the lead present to a relatively stable form in which it is highly resistant to the action of mild acids. The borate solution is preferably made up to a gravity of not exceeding 1 B. measured at 60 C. and is preferably applied at a temperature not over 50 C. I prefer that the time of application be not exceeding 20 minutes. By way of illustration and not of limitation. l have successfully employed solutions from 25 B. up to 6 B. measured at 68 (1, and temperatures of application ranging from 30 0. up to 7 5 C.

The pieces coming from the borate bath are washed and are then preferably subjected to a sodium silicate bath of about 25 Be. The silicates, phosphates and tungstates of sodium and potassium and ammonium may be alternatively employed, but the silicates. of sodium and potassium are highly preferred. The pieces are thereafter washed in the usual manner.

The pieces from the borate bath after subjection to a solution of silicates, phosphates or tungstates mentioned may be thereafter subjected to a solution of another of these compounds, for example the process may receive a phosphate bath and thereafter an application of sodium silicate, or vice versa.

The complete cycle of operations hereinbefore described may of course be repeated if desired, and this repetition may either start with the application to the goods of an aqueous solution of a tin salt, or with the subsequent application of an aqueous solution of a lead salt.

The treatment described develops a highly desirable and novel appearance, increasing the crepyness of the material. The treatment may also be utilized to controllably produce a dull appearance of the said fibers. I have found, for example, that increasing the temperature of the borate bath, or increasing the B. gravity of the same, or both, results in a more pronounced dulling of the fibers. The B. gravity and temperature limits hereinbefore recited are; however, sufficient for this purpose.

The foregoing description is for purposes of illustration and not of limitation, and it is therefore my intention that the invention be limited only by the appended claims or their equivalents, wherein I have endeavored to claim broadly. all inherent novelty.

I claim:

1. Process of weighting natural silk, which comprises weighting such silk with a tin phosphate, thereafter applying to the said silk an aqueous solution of a water soluble lead compound, and thereafter applying to the said silk an aqueous solution of an alkali metal borate selected from the group consisting of sodium and potassium borates.

2. l rocess according to claim 1, in which the water soluble lead compound is lead acetate.

3. Process of weighting natural silk, which comprises weighting such silk with a tin phosphate, thereafter applying to the said silk an aqueous solution containing a water soluble lead compound, thereafter applying to said silk an aqueous solution of an alkali metal borate selected from the group consist ing of sodium and potassium :borates, and thereafter applying to said silk an aqueous solution of a compound selected from the group including the silicates, phosphates or tungstates of sodium or potassium.

4-. Process according ,to claim 3, in which the water soluble lead compound is lead acetate.

5. Process of weighting natural silk, which comprises weighting such silk with tin phosphate, thereafter applying to said silk an aqueous solution containing a water soluble lead compound, thereafter applying to said silk an alkali metal borate selected from the group consisting of sodium and potassium borates, and thereafter applying to said silk an aqueous solution of an alkali metal silicate selected fromthe group consisting of sodium and otassium silicates.

6. rocess according to claim 5, in which the soluble lead compound is lead acetate.

7. Process of weighting natural silk, which comprises weighting such silk with a tin phosphate thereafter applying to said silk an aqueous solution containing a water soluble lead compound, thereafter applying to said silk an aqueous solution of an alkali metal borate selected from the group consisting of sodium and potassium borates, said solution having a gravity not in excess of 6 B. measured at 68 C.

8. Process according to claim 7, in which said horate solution is applied to said silk at a temperature not exceeding C.

9. Process of weighting natural silk, which comprises weighting such silk with a tin phosphate, thereafter applying to said silk an aqueous solution of lead acetate, thereafter applying to said silk an aqueous solution of an alkali metal borateselected from the group consisting of sodium and potassium borates, said solution having a gravity not in excess of 6 B. measured at 68 0., and thereafter applying to said silk an aqueous solution of a compound selected from the group consisting of the silicates, phosphates and tungstates of sodium and potassium. v

10. Process according to claim 9, in which the said borate solution is applied to said silk at a temperature not exceeding 75 C.

11. Process of weighting natural silk, which comprises weighting such silk with a tin phosphate, thereafter applying to said silk an aqueous solution of lead acetate, thereafter applying to said silk an a ueous solution of an alkali metal borate se ected from the group consisting of sodium and potassium borates, said solution having a gravit not in excess of 6B. measured at 68 and thereafter applying to said silk an aqueous solution of a compound selected from the group consisting of sodium and potassium silicates. l

'12. Process according to claim 11, in which said horate solution is applied to said silk at a temperature not in excess of 75 C.

VICTOR FROELICHER. 

